Quantum Optics with Semiconductor Double Quantum Dots

Abstract

There has been a lot of interest in solid state quantum devices such as electron spins, superconductor islands or nitrogen-vacancy centers for quantum information processing. Semiconductor double quantum dots (DQDs) have been proposed as one platform for quantum bit (qubit) implementations due to the potentially long coherence time of electron spins in materials such as silicon. Strong coupling between microwave photons and these solid state quantum devices has been achieved in circuit quantum electrodynamics (cQED) architectures. This provides one scheme for long range quantum entanglement which is important for scaling up these qubit systems. This thesis will examine hybrid cQED devices consisting of indium arsenide (InAs) DQDs that are coupled to microwave cavities. The photon emission from the DQDs, which is the main topic of the thesis, demonstrates the opportunity to study the environment such as phonons and photons that interact with this qubit candidate as well as the potential in applications such as generating quantum optics states in cavities.

We first discuss our observation of photon emission from single electron tunneling events driven by a voltage biased DQD. Later we demonstrate maser action when the photon emission rate overcomes the cavity loss rate. We first examine the emission from two DQDs that are coupled to the same cavity. We verify maser action by comparing the statistics of the emitted microwave field above and below the maser threshold. By increasing the charge-cavity coupling rate and suppressing the cavity loss channels, we achieve the maser action with only one DQD. We then study the threshold behavior of this single atom maser which reveals the contribution from tunneling between the DQD and the source-drain electrodes. Finally, we show that the emission can be stabilized by an external cavity drive. A frequency comb can be generated by modulating the DQD gain medium. Finally, we utilize the single atom maser as an on-chip microwave source for state readout of other quantum devices.